The Dark Crystals Near The Earth’s Core
A new study from the Carnegie InstitutionÂ’s Geophysical Laboratory indicates that when minerals are subjected to the intense pressures near the EarthÂ’s core, they seem to lose ability to conduct infrared light.
Infrared light contributes to the flow of heat. These findings challenge the standard theories about heat transfer in the lower mantle (the layer of molten rock that surrounds the EarthÂ’s solid core). This research may be helpful in studying “mantle plumes” — large columns of hot upwelling magma believed to produce volcanic islands like Hawaii and Iceland.
Magnesiowüstite, a common mineral within the deep Earth, transmits infrared light at normal atmospheric pressures. But when subjected to over half a million times the pressure at sea level, these crystals begin absorbing infrared light, hindering the flow of heat. The research appears in the May 26, 2006 issue of the journal Science.
In the study, crystals of magnesiowüstite were pressed using a diamond anvil cell—a chamber bound by two superhard diamonds capable of generating incredible pressure. Scientists then shone intense light through the crystals and measured the wavelengths of light that made it through. Surprisingly, the compressed crystals absorbed much of the light in the infrared range, suggesting that magnesiowüstite is a poor conductor of heat at high pressures.
“The flow of heat in Earth’s deep interior plays an important role in the dynamics, structure, and evolution of the planet,” according to Alexander Goncharov. The three primary mechanisms by which heat is likely to circulate in the deep Earth are conduction (the transfer of heat from one material or area to another), radiation, (the flow of energy via infrared light), and convection (the movement of hot material). “The relative amount of heat flow from these three mechanisms is currently under intense debate,” Goncharov adds.
The second most common mineral in the lower mantle, magnesiowüstite does not transmit heat well at high pressures. It might actually form insulating patches around much of the Earth’s core. This means that conduction and convection might be the main engines venting heat from the core.
Goncharov says, “ItÂ’s still too early to tell exactly how this discovery will affect deep-Earth geophysics…so much of what we assume about the deep Earth relies on our models of heat transfer, and this study calls a lot of that into question.”
A new study from the Carnegie InstitutionÂ’s Geophysical Laboratory indicates that when minerals are subjected to the intense pressures near the EarthÂ’s core, they seem to lose ability to conduct infrared light.
Infrared light contributes to the flow of heat. These findings challenge the standard theories about heat transfer in the lower mantle (the layer of molten rock that surrounds the EarthÂ’s solid core). This research may be helpful in studying “mantle plumes” — large columns of hot upwelling magma believed to produce volcanic islands like Hawaii and Iceland.
Magnesiowüstite, a common mineral within the deep Earth, transmits infrared light at normal atmospheric pressures. But when subjected to over half a million times the pressure at sea level, these crystals begin absorbing infrared light, hindering the flow of heat. The research appears in the May 26, 2006 issue of the journal Science.
In the study, crystals of magnesiowüstite were pressed using a diamond anvil cell—a chamber bound by two superhard diamonds capable of generating incredible pressure. Scientists then shone intense light through the crystals and measured the wavelengths of light that made it through. Surprisingly, the compressed crystals absorbed much of the light in the infrared range, suggesting that magnesiowüstite is a poor conductor of heat at high pressures.
“The flow of heat in Earth’s deep interior plays an important role in the dynamics, structure, and evolution of the planet,” according to Alexander Goncharov. The three primary mechanisms by which heat is likely to circulate in the deep Earth are conduction (the transfer of heat from one material or area to another), radiation, (the flow of energy via infrared light), and convection (the movement of hot material). “The relative amount of heat flow from these three mechanisms is currently under intense debate,” Goncharov adds.
The second most common mineral in the lower mantle, magnesiowüstite does not transmit heat well at high pressures. It might actually form insulating patches around much of the Earth’s core. This means that conduction and convection might be the main engines venting heat from the core.
Goncharov says, “ItÂ’s still too early to tell exactly how this discovery will affect deep-Earth geophysics…so much of what we assume about the deep Earth relies on our models of heat transfer, and this study calls a lot of that into question.”
